fs/isofs/namei.c

/* */
This source file includes following definitions.
isofs_match
isofs_find_entry
isofs_lookup
   1 /*
   2  *  linux/fs/isofs/namei.c
   3  *
   4  *  (C) 1992  Eric Youngdale Modified for ISO9660 filesystem.
   5  *
   6  *  (C) 1991  Linus Torvalds - minix filesystem
   7  */
   8 
   9 #include <linux/sched.h>
  10 #include <linux/iso_fs.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/stat.h>
  14 #include <linux/fcntl.h>
  15 #include <asm/segment.h>
  16 #include <linux/malloc.h>
  17 
  18 #include <linux/errno.h>
  19 
  20 /*
  21  * ok, we cannot use strncmp, as the name is not in our data space.
  22  * Thus we'll have to use isofs_match. No big problem. Match also makes
  23  * some sanity tests.
  24  *
  25  * NOTE! unlike strncmp, isofs_match returns 1 for success, 0 for failure.
  26  */
  27 static int isofs_match(int len,const char * name, char * compare, int dlen)
     /*  */
  28 {
  29         register int same __asm__("ax");
  30         
  31         if (!compare) return 0;
  32         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  33         if (!len && (compare[0]==0) && (dlen==1))
  34                 return 1;
  35         
  36         if (compare[0]==0 && dlen==1 && len == 1)
  37                 compare = ".";
  38         if (compare[0]==1 && dlen==1 && len == 2) {
  39                 compare = "..";
  40                 dlen = 2;
  41         };
  42 #if 0
  43         if (len <= 2) printk("Match: %d %d %s %d %d \n",len,dlen,compare,de->name[0], dlen);
  44 #endif
  45         
  46         if (dlen != len)
  47                 return 0;
  48         __asm__("cld\n\t"
  49                 "repe ; cmpsb\n\t"
  50                 "setz %%al"
  51                 :"=a" (same)
  52                 :"0" (0),"S" ((long) name),"D" ((long) compare),"c" (len)
  53                 :"cx","di","si");
  54         return same;
  55 }
  56 
  57 /*
  58  *      isofs_find_entry()
  59  *
  60  * finds an entry in the specified directory with the wanted name. It
  61  * returns the cache buffer in which the entry was found, and the entry
  62  * itself (as an inode number). It does NOT read the inode of the
  63  * entry - you'll have to do that yourself if you want to.
  64  */
  65 static struct buffer_head * isofs_find_entry(struct inode * dir,
     /*  */
  66         const char * name, int namelen, int * ino, int * ino_back)
  67 {
  68         unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
  69         unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
  70         unsigned int block, i, f_pos, offset, inode_number;
  71         struct buffer_head * bh;
  72         void * cpnt = NULL;
  73         unsigned int old_offset;
  74         unsigned int backlink;
  75         int dlen, rrflag, match;
  76         char * dpnt;
  77         struct iso_directory_record * de;
  78         char c;
  79 
  80         *ino = 0;
  81         if (!dir) return NULL;
  82         
  83         if (!(block = dir->u.isofs_i.i_first_extent)) return NULL;
  84   
  85         f_pos = 0;
  86 
  87         offset = f_pos & (bufsize - 1);
  88         block = isofs_bmap(dir,f_pos >> bufbits);
  89 
  90         if (!block || !(bh = bread(dir->i_dev,block,bufsize))) return NULL;
  91   
  92         while (f_pos < dir->i_size) {
  93                 de = (struct iso_directory_record *) (bh->b_data + offset);
  94                 backlink = dir->i_ino;
  95                 inode_number = (block << bufbits) + (offset & (bufsize - 1));
  96 
  97                 /* If byte is zero, this is the end of file, or time to move to
  98                    the next sector. Usually 2048 byte boundaries. */
  99                 
 100                 if (*((unsigned char *) de) == 0) {
 101                         brelse(bh);
 102                         offset = 0;
 103                         f_pos = ((f_pos & ~(ISOFS_BLOCK_SIZE - 1))
 104                                  + ISOFS_BLOCK_SIZE);
 105                         block = isofs_bmap(dir,f_pos>>bufbits);
 106                         if (!block || !(bh = bread(dir->i_dev,block,bufsize)))
 107                                 return 0;
 108                         continue; /* Will kick out if past end of directory */
 109                 }
 110 
 111                 old_offset = offset;
 112                 offset += *((unsigned char *) de);
 113                 f_pos += *((unsigned char *) de);
 114 
 115                 /* Handle case where the directory entry spans two blocks.
 116                    Usually 1024 byte boundaries */
 117                 if (offset >= bufsize) {
 118                         cpnt = kmalloc(1 << ISOFS_BLOCK_BITS, GFP_KERNEL);
 119                         memcpy(cpnt, bh->b_data, bufsize);
 120                         de = (struct iso_directory_record *)
 121                           ((char *)cpnt + old_offset);
 122                         brelse(bh);
 123                         offset = f_pos & (bufsize - 1);
 124                         block = isofs_bmap(dir,f_pos>>bufbits);
 125                         if (!block || !(bh = bread(dir->i_dev,block,bufsize))) {
 126                                 kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
 127                                 return 0;
 128                         };
 129                         memcpy((char *)cpnt+bufsize,bh->b_data,bufsize);
 130                 }
 131                 
 132                 /* Handle the '.' case */
 133                 
 134                 if (de->name[0]==0 && de->name_len[0]==1) {
 135                         inode_number = dir->i_ino;
 136                         backlink = 0;
 137                 }
 138                 
 139                 /* Handle the '..' case */
 140 
 141                 if (de->name[0]==1 && de->name_len[0]==1) {
 142 #if 0
 143                         printk("Doing .. (%d %d)",
 144                                dir->i_sb->s_firstdatazone << bufbits,
 145                                dir->i_ino);
 146 #endif
 147                         if((dir->i_sb->u.isofs_sb.s_firstdatazone
 148                             << bufbits) != dir->i_ino)
 149                                 inode_number = dir->u.isofs_i.i_backlink;
 150                         else
 151                                 inode_number = dir->i_ino;
 152                         backlink = 0;
 153                 }
 154     
 155                 dlen = de->name_len[0];
 156                 dpnt = de->name;
 157                 /* Now convert the filename in the buffer to lower case */
 158                 rrflag = get_rock_ridge_filename(de, &dpnt, &dlen, dir);
 159                 if (rrflag) {
 160                   if (rrflag == -1) goto out; /* Relocated deep directory */
 161                 } else {
 162                   if(dir->i_sb->u.isofs_sb.s_mapping == 'n') {
 163                     for (i = 0; i < dlen; i++) {
 164                       c = dpnt[i];
 165                       if (c >= 'A' && c <= 'Z') c |= 0x20;  /* lower case */
 166                       if (c == ';' && i == dlen-2 && dpnt[i+1] == '1') {
 167                         dlen -= 2;
 168                         break;
 169                       }
 170                       if (c == ';') c = '.';
 171                       de->name[i] = c;
 172                     }
 173                     /* This allows us to match with and without a trailing
 174                        period.  */
 175                     if(dpnt[dlen-1] == '.' && namelen == dlen-1)
 176                       dlen--;
 177                   }
 178                 }
 179                 match = isofs_match(namelen,name,dpnt,dlen);
 180                 if (cpnt) {
 181                         kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
 182                         cpnt = NULL;
 183                 }
 184 
 185                 if(rrflag) kfree(dpnt);
 186                 if (match) {
 187                         if(inode_number == -1) {
 188                                 /* Should only happen for the '..' entry */
 189                                 inode_number = 
 190                                         isofs_lookup_grandparent(dir,
 191                                            find_rock_ridge_relocation(de,dir));
 192                                 if(inode_number == -1){
 193                                         /* Should never happen */
 194                                         printk("Backlink not properly set.\n");
 195                                         goto out;
 196                                 }
 197                         }
 198                         *ino = inode_number;
 199                         *ino_back = backlink;
 200                         return bh;
 201                 }
 202         }
 203  out:
 204         if (cpnt)
 205                 kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
 206         brelse(bh);
 207         return NULL;
 208 }
 209 
 210 int isofs_lookup(struct inode * dir,const char * name, int len,
     /*  */
 211         struct inode ** result)
 212 {
 213         int ino, ino_back;
 214         struct buffer_head * bh;
 215 
 216 #ifdef DEBUG
 217         printk("lookup: %x %d\n",dir->i_ino, len);
 218 #endif
 219         *result = NULL;
 220         if (!dir)
 221                 return -ENOENT;
 222 
 223         if (!S_ISDIR(dir->i_mode)) {
 224                 iput(dir);
 225                 return -ENOENT;
 226         }
 227 
 228         ino = 0;
 229         if (dir->i_dev == cache.dev && 
 230             dir->i_ino == cache.dir &&
 231             len == cache.dlen && 
 232             isofs_match(len, name, cache.filename, cache.dlen))
 233           {
 234             ino = cache.ino;
 235             ino_back = dir->i_ino;
 236             /* These two cases are special, but since they are at the start
 237                of the directory, we can just as easily search there */
 238             if (cache.dlen == 1 && cache.filename[0] == '.') ino = 0;
 239             if (cache.dlen == 2 && cache.filename[0] == '.' && 
 240                 cache.filename[1] == '.') ino = 0;
 241           };
 242 
 243         if (!ino) {
 244           if (!(bh = isofs_find_entry(dir,name,len, &ino, &ino_back))) {
 245             iput(dir);
 246             return -ENOENT;
 247           }
 248           brelse(bh);
 249         };
 250 
 251         if (!(*result = iget(dir->i_sb,ino))) {
 252                 iput(dir);
 253                 return -EACCES;
 254         }
 255 
 256         /* We need this backlink for the ".." entry unless the name that we
 257            are looking up traversed a mount point (in which case the inode
 258            may not even be on an iso9660 filesystem, and writing to
 259            u.isofs_i would only cause memory corruption).
 260         */
 261         
 262         if (ino_back && !(*result)->i_pipe && (*result)->i_sb == dir->i_sb) {
 263           (*result)->u.isofs_i.i_backlink = ino_back; 
 264         }
 265         
 266         iput(dir);
 267         return 0;
 268 }
/* */
root/fs/isofs/namei.c

DEFINITIONS
